Hermetically sealed travel switch

Abstract

The present invention discloses an airtight sealed travel switch. Its driving assembly includes a button installed in the guiding hole of the upper housing sleeve and a nut seat screwed into the lower housing sleeve. A return spring is press-fitted between the button and the nut seat, and a metal bellows is sleeved on the return spring. The front and rear ends of the metal bellows are respectively connected and laser welded to the button and the lower housing sleeve. Its conductive assembly includes a metal core rod passing through the return spring. The front end of the metal core rod is screwed into the threaded hole of the button, and the rear part of the metal core rod passes through the nut seat and enters the lower housing sleeve. An insulating layer is covered on the metal core rod, and a conductive ring is nested on the insulating layer. Its contact spring assembly includes a spring sleeve seat arranged in the lower housing sleeve. The spring sleeve seat is sleeved on the metal core rod. Two pairs of upper and lower windows that are misaligned by 90° are provided on the spring sleeve seat and are respectively aligned with the conductive rings. A pair of long spring pieces and a pair of short spring pieces are respectively provided corresponding to the upper and lower pairs of windows. The "V"-shaped contacts on each spring piece are aligned with the corresponding windows.

Description

Technical Field

[0001] The present invention relates to circuit control components, and specifically to an airtight sealed travel switch. Background Art

[0002] A travel switch is an electrical appliance that switches a circuit according to the travel position of a moving part. Its overall structure includes a driving mechanism, a conductive component, a contact spring element, and an output interface.

[0003] In an electrical control system, the switch is installed at a preset position. When an external pressure is applied to the driving mechanism of the travel switch, the conductive component reciprocates inside the contact spring element to achieve the on, off (or conversion) of the contacts, thereby completing the circuit switching and providing functions such as electrical conversion signals for the system.

[0004] In the aerospace field, the travel switches supporting the electrical control system have to withstand harsh space environments such as vacuum discharge, vacuum outgassing, and thermal vacuum.

[0005] Some waterproof travel switches in the prior art, although having certain watertight performance, are not suitable for use in the space environment, and their ability to resist mechanical properties is also relatively weak. Summary of the Invention

[0006] The present invention proposes an airtight sealed travel switch, aiming to achieve the airtight sealing performance and the ability to resist high-strength mechanical environments of the travel switch.

[0007] The airtight sealed travel switch that can achieve the above purpose includes a driving component, a conductive component, and a contact spring component. The differences are as follows:

[0008] 1. The driving component includes a button slidably installed in the guiding hole at the top of the upper housing sleeve and a nut seat screwed into the shell nozzle at the top of the lower housing sleeve. The upper housing sleeve is threadedly connected to the lower housing sleeve. A return spring is press-fitted between the spring hole at the bottom of the button and the nut seat in the shell nozzle. A metal bellows is sleeved on the return spring. The upper end of the metal bellows is sleeved and laser-welded to the lower part of the button, and the lower end of the metal bellows is sleeved and laser-welded to the shell nozzle.

[0009] 2. The conductive component includes a metal core rod passing through the return spring. The upper end of the metal core rod is screwed into the threaded hole at the bottom of the button. The middle and lower parts of the metal core rod pass through the nut seat and enter the lower housing sleeve. The middle and lower parts of the metal core rod are coated with an insulating layer, and a conductive ring is nested on the insulating layer.

[0010] 3. The contact spring assembly includes a spring sleeve seat disposed within the lower housing sleeve. The upper part of the spring sleeve seat is sleeved on the middle and lower part of the metal core rod. A spring cover is press-fitted at the lower part of the spring sleeve seat. The spring cover is screwed into the lower housing sleeve by a plug to tightly press the spring sleeve seat upward. The spring sleeve seat is provided with front and rear windows Ⅰ and left and right windows Ⅱ that are offset by 90° both vertically and horizontally. Corresponding to the front and rear windows Ⅰ and the left and right windows Ⅱ, there are respectively front and rear long spring pieces and left and right short spring pieces. The lower parts of the spring pieces are clamped between the spring cover and the spring seat, and the "V"-shaped contact heads at the upper parts of the spring pieces are aligned with the corresponding windows.

[0011] 4. A gas seal plate with an air extraction hole is laser welded to the bottom of the lower housing sleeve. A pin-type plug is hermetically arranged on the gas seal plate. The four pins of the pin-type plug are respectively connected to the front and rear long spring pieces and the left and right short spring pieces through corresponding insulated cables.

[0012] The present invention can achieve conversion between two circuits:

[0013] 1. At the return position of the button, the front and rear "V"-shaped contact heads of the front and rear long spring pieces are connected to the conductive ring through the front and rear windows Ⅰ to achieve the conduction of one circuit.

[0014] 2. At the pressed position of the button, the front and rear "V"-shaped contact heads of the left and right short spring pieces are connected to the conductive ring through the left and right windows Ⅱ to achieve the conduction of another circuit.

[0015] The present invention can operate in a vacuum environment in the following way: after evacuating the internal spaces of the metal bellows and the lower housing sleeve through the air extraction hole, a steel ball is used for tin sealing or laser sealing on the air extraction hole.

[0016] A further protective measure (to protect the metal bellows from moisture erosion) is: a sealing ring Ⅰ is provided between the button and the guiding hole of the upper housing sleeve, and a sealing ring Ⅱ is provided between the connecting surface of the upper housing sleeve and the lower housing sleeve. The internal space of the upper housing sleeve is sealed through the sealing ring Ⅰ and the sealing ring Ⅱ.

[0017] For the convenience of installation, a flange ring plate is provided on the upper housing sleeve.

[0018] The beneficial effects of the present invention:

[0019] In the hermetically sealed travel switch of the present invention, a hermetically sealed structure and a "V"-shaped contact sliding contact structure are adopted, so that the travel switch has hermetic performance while being resistant to high vibration and strong impact. Specifically, it is manifested as:

[0020] 1. The hermetic sealing performance is achieved through the application of the metal bellows in the travel switch.

[0021] 2. The connection between components is reliable and the assembly is simple.

[0022] 3. The overall structure has excellent resistance to mechanical environments and can adapt to operating conditions with high vibration and strong impact.

[0023] 4. The travel switch can meet the usage requirements in space environments such as vacuum gas outlet, vacuum discharge, and vacuum irradiation.

[0024] 5. Sealing rings and insulating layers are made of high-temperature resistant materials, enabling the high-temperature airtight function of the travel switch.

[0025] 6. After the interior of the travel switch is evacuated, it can solve the problem of unstable contact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the front view of an embodiment of the present invention.

[0027] Figure 2 is Figure 1 the structural schematic diagram of the drive assembly in the embodiment.

[0028] Figure 3 is Figure 1 the structural schematic diagram of the conductive assembly in the embodiment.

[0029] Figure 4 is Figure 1 the structural schematic diagram of the contact spring assembly in the embodiment.

[0030] Drawing number identification: 1. Upper housing sleeve; 1-1. Flange ring plate; 2. Button; 2-1. Threaded hole; 2-2. Spring hole, 3. Lower housing sleeve; 3-1. Shell nozzle; 4. Nut seat; 5. Return spring; 6. Metal bellows; 7. Spring sleeve seat; 7-1. Window Ⅰ; 7-2. Window Ⅱ; 8. Spring cover; 9. Sealing ring Ⅱ; 10. Long spring piece; 11. Short spring piece; 12. Metal core rod; 12-1. Insulating layer; 12-2. Conductive ring; 13. Air sealing plate; 14. Pin plug; 15. Steel ball; 16. Sealing ring Ⅰ; 17. Plug screw. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions of the present invention will be further described below in conjunction with the embodiments shown in the drawings.

[0032] The airtight sealed travel switch of the present invention includes a drive assembly, a conductive assembly, a contact spring assembly, and an airtight connector.

[0033] The driving assembly includes an upper housing sleeve 1, a lower housing sleeve 3, a button 2, a metal bellows 6 and a return spring 5. The fine-thread internal thread at the lower end socket of the upper housing sleeve 1 is screwed onto the fine-thread external thread at the outer edge of the top of the lower housing sleeve 3, and the threaded connection surface is sealed by a seal ring II 9. A nut seat 4 is internally screwed onto the lower part of the nozzle 3-1 at the center of the top of the lower housing sleeve 3, and the lower sleeve hole of the lower housing sleeve 3 is an internal threaded hole. The button 2 includes a sliding part slidably disposed in the guiding hole (coaxial with the nozzle 3-1) at the top of the upper housing sleeve 1 and a limiting part positioned upward within the upper housing sleeve 1 at the top of the upper housing sleeve 1. A seal ring I 16 is provided between the sliding part of the button 2 and the guiding hole. Threaded holes 2-1 and spring holes 2-2 coaxial up and down are provided in the limiting part of the button 2. A return spring 5 is provided between the upper and lower ends of the return spring 5 and is pre-tightened between the bottom of the spring hole 2-2 and the nut seat 4. The metal bellows 6 is sleeved on the return spring 5. The upper end pipe orifice of the metal bellows 6 is sleeved with and laser welded and sealed in a circumferential manner to the limiting part of the button 2. The lower end pipe orifice of the metal bellows 6 is sleeved with and laser welded and sealed in a circumferential manner to the nozzle 3-1, as Figure 1 , Figure 2 shown.

[0034] The conductive assembly includes a metal core rod 12 passing through the return spring 5. The upper end of the metal core rod 12 is a screw head. The middle and lower part of the rod body of the metal core rod 12 is coated with an insulating layer 12-1 (by integral insert injection molding, and a structure for preventing the rotation of the insulating layer 12-1 is provided at the injection part). An annular groove is provided at the lower part of the insulating layer 12-1. A conductive ring 12-2 is nested in the annular groove. The lower end of the metal core rod 12 is a flat-head or cross-head with a rotatable rod body. The screw head of the metal core rod 12 is screwed upward into the threaded hole 2-1 of the button 2. The insulating part of the metal core rod 12 passes downward through the inner hole of the nut seat 4 and enters the lower housing sleeve 3, as Figure 1 , Figure 3 shown.

[0035] The contact spring assembly includes a spring sleeve base 7, a spring cover 8, a pair of long spring pieces 10 and a pair of short spring pieces 11. The spring sleeve base 7 is arranged in the lower housing sleeve 3, and the sleeve hole (guide inner hole) of the spring sleeve base 7 is sleeved upward on the insulating part of the metal core rod 12. The spring cover 8 is press-fitted on the lower part of the spring sleeve base 7. The spring cover 8 is fixedly installed in the plug hole of the plug 17, and the plug 17 is screwed into the internal thread hole of the lower housing sleeve 3. The plug 17 screwed in place presses the upper end of the spring sleeve base 7 tightly on the nut seat 4 through the spring cover 8. A pair of front and rear windows Ⅰ7-1 are provided in the upper part of the spring sleeve base 7, which are misaligned by 90° with the front and rear windows Ⅰ7-1. A pair of left and right windows Ⅱ7-2 are provided in the lower part of the spring sleeve base 7. The front and rear long spring pieces 10 are arranged corresponding to the front and rear windows Ⅰ7-1. The lower parts of the long spring pieces 10 are clamped between the spring sleeve base 7 and the spring cover 8. The "V"-shaped contacts at the upper parts of the long spring pieces 10 are elastically pressed into the corresponding windows Ⅰ7-1 and act on the metal core rod 12. The left and right short spring pieces 11 are arranged corresponding to the left and right windows Ⅱ7-2. The lower parts of the short spring pieces 11 are clamped between the spring sleeve base 7 and the spring cover 8. The "V"-shaped contacts at the upper parts of the short spring pieces 11 are elastically pressed into the corresponding windows Ⅱ7-2 and act on the metal core rod 12, as Figure 1 , Figure 4 shown.

[0036] The gas-sealed connector includes a pin plug 14 that penetrates through and is sealed and installed on the gas seal plate 13. An air extraction hole is provided on the gas seal plate 13 beside the pin plug 14. The gas seal plate 13 is screwed and installed at the lower end of the internal thread hole of the lower housing sleeve 3 through its outer circumferential thread and is laser welded and sealed around. Inside the lower housing sleeve 3, the upper ends of the four pins of the pin plug 14 are respectively connected to four insulated cables. Two of the insulated cables are respectively connected to the front and rear long spring pieces 10, and the other two insulated cables are respectively connected to the left and right short spring pieces 11. After the internal space of the metal bellows 6 and the internal space of the lower housing sleeve 3 are evacuated through the air extraction hole, the air extraction hole is blocked with a steel ball 15, and the steel ball 15 is sealed to the air extraction hole by soldering or laser sealing, as Figure 1 shown.

[0037] The present invention is installed in place in the electrical control system of the equipment through the flange ring plate 1-1 of the upper housing sleeve 1. The working principle of its circuit conversion is as follows:

[0038] 1. At the upward return position of the button 2 (the metal core rod 12 slides upward accordingly), the conductive ring 12-2 on the insulating layer 12-1 is opposite to the front and rear windows Ⅰ7-1 on the upper part of the spring sleeve base 7. The front and rear "V"-shaped contacts of the front and rear long spring pieces 10 are connected to the conductive ring 12-2 through the front and rear windows Ⅰ7-1 to form a circuit path Ⅰ. At this time, the left and right "V"-shaped contacts of the left and right short spring pieces 11 act on the insulating layer 12-1 through the left and right windows Ⅱ7-2 to disconnect the circuit path Ⅱ.

[0039] 2. At the downward pressing position of the button 2 (where the metal core rod 12 slides downward accordingly), the conductive ring 12-2 on the insulating layer 12-1 is connected to the left and rear windows II 7-2 at the lower part of the spring sleeve seat 7. The left and right "V"-shaped contacts of the left and right short spring pieces 11 are connected to the conductive ring 12-2 through the left and right windows II 7-2 to conduct the circuit path II. At this time, the front and rear "V"-shaped contacts of the front and rear long spring pieces 10 act on the insulating layer 12-1 through the front and rear windows I 7-1 to disconnect the circuit path I.

Claims

1. Hermetically sealed travel switch, comprising a driving assembly, a conductive assembly and a contact spring assembly, characterized in that: The driving assembly includes a button (2) slidably mounted in the guiding hole at the top of the upper housing sleeve (1) and a nut seat (4) screwed into the nozzle (3-1) at the top of the lower housing sleeve (3). The upper housing sleeve (1) is threadedly connected to the lower housing sleeve (3). A return spring (5) is press-fitted between the spring hole at the bottom of the button (2) and the nut seat (4) in the nozzle (3-1). A metal bellows (6) is sleeved on the return spring (5). The upper end of the metal bellows (6) is sleeved and laser-welded to the lower part of the button (2), and the lower end of the metal bellows (6) is sleeved and laser-welded to the nozzle. The conductive assembly includes a metal core rod (12) passing through the return spring (5). The upper end of the metal core rod (12) is screwed into the screw hole at the bottom of the button. The middle and lower part of the metal core rod (12) passes through the nut seat (4) and enters the lower housing sleeve (3). The middle and rear part of the metal core rod (12) is coated with an insulating layer (12-1), and a conductive ring (12-2) is nested on the insulating layer (12-1). The contact spring assembly includes a spring sleeve seat (7) provided in the lower housing sleeve (3). The upper part of the spring sleeve seat (7) is sleeved on the middle and lower part of the metal core rod (12). A spring cover (8) is press-fitted at the lower part of the spring sleeve seat (7). The spring cover (8) is screwed into the lower housing sleeve (3) through a plug (17) to tightly push up the spring sleeve seat (7). The spring sleeve seat (7) is provided with front and rear windows I (7-1) and left and right windows II (7-2) which are 90° offset up and down. Corresponding to the front and rear windows I (7-1) and left and right windows II (7-2), front and rear long spring pieces (10) and left and right short spring pieces (11) are respectively provided. The lower parts of the spring pieces are clamped between the spring cover (8) and the spring sleeve seat (7), and the "V"-shaped contacts at the upper parts of the spring pieces are located in the corresponding windows. A gas sealing plate (13) with an air extraction hole is laser-welded at the bottom of the lower housing sleeve (3). A pin plug (14) is hermetically arranged on the gas sealing plate (13). The four pins of the pin plug (14) are respectively connected to the front and rear long spring pieces (10) and left and right short spring pieces (11) through corresponding insulating cables. In the return position of the button (2), the front and rear "V"-shaped contacts of the front and rear long spring pieces (10) are connected to the conductive ring (12-2) through the front and rear windows I (7-1). In the pressed position of the button (2), the left and right short spring pieces (11) are connected to the conductive ring (12-2) through the left and right windows II (7-2).

2. The hermetic sealed travel switch according to claim 1, wherein: After evacuating the internal space of the metal bellows (6) and the internal space of the lower housing sleeve (3) through the air extraction hole, a steel ball (15) is used for tin sealing or laser sealing treatment on the air extraction hole.

3. The hermetic sealed travel switch according to claim 2, characterized in that: A sealing ring I (16) is provided between the button (2) and the guiding hole of the upper housing sleeve (1), and a sealing ring II (9) is provided between the connecting surface of the upper housing sleeve (1) and the lower housing sleeve (3).

4. The hermetically sealed travel switch according to claim 1, characterized in that: The upper housing sleeve (1) is provided with a flange ring plate (1-1).

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